We have performed a study of the isovector, octet, and singlet axial charges of the proton in an extended chiral constituent quark model, where all the possible $uudq\overline{q}$ ($q=u$, $d$, $s$) five-quark Fock components in the proton wave function are taken into account. The ${}^3{P}_0$ quark-antiquark creation mechanism is assumed to account for the transition coupling between three- and five-quark components in proton, and the corresponding transition coupling strength is fixed by fitting the intrinsic sea flavor asymmetry $\overline{d}-\overline{u}$ data for proton. Accordingly, with all the parameters fixed by empirical values, the probabilities of the intrinsic five-quark Fock components in proton wave function should be $\sim 30–50\%$, which lead to the numerical results for quark spin $\mathrm{\Delta }u$, $\mathrm{\Delta }d$, and $\mathrm{\Delta }s$, as well the axial charges of proton consistent with the experimental data and predictions by other theoretical approaches.

• Received 20 April 2021
• Accepted 1 June 2021

DOI:https://doi.org/10.1103/PhysRevD.103.114018

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Published by the American Physical Society